LARGE SCALE PRODUCTION OF SILVER NANOPARTICLES BY TRICHODERMA REESEI WITH ANTIMICROBIAL AND ANTIVIRAL POTENCIAL

Silver nanoparticles (AgNP) biosynthesis mediated by Trichoderma reesei present proteins that can reduce metals. Previous studies conducted by our research group identified three candidate proteins capping AgNPs: Tr_73631, Tr_77288 and Tr_60784. In this context, this study proposes phylogenetically characterization of oxidoreductases from T. reesei potentially responsible for silver reduction to nanoparticles’ synthesis. Initially we used the T. reesei supernatant from cultivation in potato-dextrose medium to silver reduction and evaluated the formation of AgNPs during 16 days through measurement of the absorbance from 300nm to 1000nm in Microplate Reader. Then a BlastP was made with each protein to find homologous. These proteins were used to build a phylogenetic tree using ClustalW for alignment and the phylogeny was inferred using the Maximum Likelihood method and Jones-Taylor-Thornton in MEGA12. The highest absorbance in the expected 400–430 nm range was observed after 15 days of incubation. The tree revealed 5 clades and each one of AgNPs were grouped in different clades. The closest protein from each three capping AgNPs found in the tree and already experimentally characterized were used for structural comparison. The protein structures were predicted using AlphaFold3, and the structural quality was validated. To analyse the structural similarity between our targets and their homology, we made RMSD calculation in ChimeraX and used the PrankWeb to predict putative active sites enabling the comparison of residues in potentially functional regions. At least three homologs found in BlastP were used to build the phylogenetic tree. The structures predicted have good values of pTM, ipTM, pLDDT, as well more than 90% of residues in favored and allowed regions in Ramachandran Plot. The comparison between structures of our targets and their homologs (RMSD) presented values <2Å for all three comparisons made in ChimeraX and the PrankWeb results showed high conservation of residues present in the binding site. This data allows us to infer that the function of the three T. reesei is indeed metal reduction, which suggests the role in silver reduction in AgNP synthesis.